It was Christmastime in Tehran, and forecasters were predicting another early snow. On a cold day last December at the bazaar in Tajrish, the wealthy historic neighborhood in northern Tehran, shoppers avoided the exposed alleyway stalls and instead headed for the warmth of the nearby mini-malls, which were as overheated as any in the United States. Inside one, kids gathered around the window of a Christmas shop to gaze at the ornaments and plastic Santas inside. A few other shops also had Christmas decorations -- perfectly legal in the Islamic Republic, even if the religious authorities frown on them. Christians are free to celebrate as they wish -- there are even Christmas trees for sale on the sidewalks in the Armenian neighborhoods of Tehran.

The decorations contrasted sharply with the thousands of black and green "Ya Hossein" flags fluttering outside virtually every street-side shop, celebrating Shia Islam's Imam. There were the vans and cruisers of the Gasht-e Ershad, the morality police, who guard Persian society from sartorial affronts to Islam. This year they extended their unwelcome presence well into the winter months (they normally appear in the spring, when coats come off for the season, and are gone by the early summer), lest a stray strand of hair poke from underneath a woman's scarf, or, worse yet, her coat not quite reach her knees.

So it was Christmas, but it was also Moharram, the Arabic name for the month in which Hossein, the grandson of the prophet Muhammad and patron saint of Shias, was martyred in Karbala. It is the most holy month for Shias, celebrating as it does their most venerated saint, whose martyrdom is their very raison d'être. As some Iranians went about their daily business, shopping for food and household items, the more pious attended mosques for mourning ceremonies -- rites that for hundreds of years nothing, not even international crises, revolutions, or the winds of war could prevent,